Grinder workstand



Nov. 15, 1938.

TM. HOKANSON GRINDER WORKSTAND Filed Oct. 26, 1936 INVEYNTOR. I yaw ATTORNEY.

Patented Nov. 15, 1938 PATENT OFFICE GRINDER WORKSTAND Martin Hokanson, Duluth, Minn., assignor to Eidco, Inc., Duluth, Minnesota Minn., a corporation of Application October 26, 1936, Serial No. 107,564

3 Claims.

This invention relates to work tables or supports applicable to a common bench grinder, and relates particularly to improvements in a support and associated instrumentalities for suc- 5, cessful and most conveniently operated means for the grinding of drill hits such as used in rock drilling or the like, and particularly wherein relatively short drill heads are used on more or less extended and detachable shanks, so that the 10' head only is necessary for consideration and manipulation during the grinding and sharpening operation.

Such a drill bit is comparatively common in the art. It is obvious, however, that the cutting face 151 of the bit may be of varied form or shape and still the convenience of the instant form of work table or support be equally appreciated and utilized.

One of the principal objects of the invention is to provide a work supporting table upon which 20 a drill bit head may be most conveniently rotated manually while being sharpened.

Another object of the invention is to provide selective and dependable setting means for predetermining the angle of the ultimate sharpen- 25,, mg of the bit.

Referring now to the accompanying drawing, forming part of this application, and wherein like reference characters indicate like parts:

Figure 1 is a front elevation of a portion of a common bench grinder having one embodiment of the invention applied thereto.

Figure 2 is an enlarged elevation, at right angles to that shown in Figure 1 of the grinding angle gauge.

Figure 3 is an enlarged plan View of the free end of the table supporting bracket.

In the drawing, l represents a common electrically operated bench grinder usually equipped with a grinding wheel upon either end of the armature shaft thereof, and in this instance I have illustrated but one end and secured thereto a V-shaped grinding wheel 2 suitable for the purpose intended, the same being protected by the adjustable guard housing illustrated at 3 and common in the art. Such guard housing usually carries an angularly depending projection 4 provided with a tool rest not shown, but to which projection I have shown attached a bracket 5, the extreme free end of which is of 50 somewhat L-shape as at 6 (see Fig. 3) and which free terminal is split as at l and provided with an internally screw threaded hole 8 at the inner termination of the slot 1, into which hole is screw threadedly mounted the stem 9 of the work 55 table It); The object of the bifurcated portion beyond the hole obviously being for the purpose of selectively clamping the work table in any desired rotatable position, as by the crank head bolt 30. It will be noted that the bracket is adjustable upon the extension 4 in the usual manner, as by manipulation of the bolt II. The table II) is for the convenient support of the work, which, in this instance, is illustrated in dotted lines at 12 as being a drill head bit and for convenience in illustration is shown as one having arcuate cutting edges to be ground with inclined outer surfaces indicated at [3. It is apparent thus far that in order to sharpen such an inclined surface the bit head will have to ap proach the grinder while in upright position and horizontally and with the plane of its cutting face materially above the lower circumferential edge of the grinding wheel, and the distance above such lower point will determine the angle of the grinding.

Now in order to provide a gauge for such purpose, prior to the initial operation of the grinding and to insure subsequent operations being uniform, I have provided a gauge carried upon the guard housing 3' of the grinder and pivotally attached concentrically coincident with the axis of the armature of the grinder upon which the grinding wheel is attached, such connection being accomplished as by the pin or stud I4 being screw-threadedly applied to the housing for pivotal support of the gauge plate l5 externally of which the jam nut I6 is screw threaded upon the pin l4 so that by the slacking oif of this nut the gauge plate may be selectively rotated and again held securely in any desired position by the nut. Also upon the outermost end of the pin or stud I4 is screw threadedly mounted the sleeve nut I! having a diametrically disposed through hole just outwardly of the outer end of the pin after the nut I! is mounted thereupon, and through which hole is adjustably carried the pointer stem I8, the adjustability of which is accomplished by the thumb screw l9 being mounted within the bore of the nut l1 and engageable with the stem I8 when in the nut. The stem I8 is flattened somewhat as at 20, longitudinally thereof for firm holding thereof by the thumb screw I9.

The operable condition of the gauge plate 15 is obviously at an angle as shown in Figure 2 which may be set in various ways hereinafter described, and is provided with a plurality of screw threaded holes as indicated at 2|, each hole carrying adjacent thereto numerals indicating various angles at which the grinding of the wheel may be accomplished upon a drill head. Common to all of the holes 2| is provided a thumb and finger manipulated pin 22 having a screw threaded end applicable to or from any one of the holes, this pin being for the purpose of limiting the movement of the pointer stem or arm which carries upon its extreme free end the pointer 23, it being adjustable back and forth in preferably the same manner as the arm is adjustable in the sleeve l1 and such adjustment obviously being for the accommodationof different shaped and diametered grinding wheels. This gauge apparatus, including the pointer, arm and plate, may be set in the following manner: Assuming that it 'is desirable to sharpen the outer wall of the cutting face of a bit head at an angle of 45, and that the gauge plate I5 is loose upon its supportingv bolt l4 and carrying the pin 22 within the hole designated at 90, which represents the angle of the line to the angle of grinding, the arm 18 may be swung on its pivotal support up to a 45 position from the vertical, as for example indicated by the line 24, and which will swing the center line of the plate I5 somewhat above said 45 line 24, when the attachment of the plate i5 may be tightened as by the nut l6 upon the pin or stud l4 so that it will remain in such position. The pointer 23 being swung concentrically with the extreme peripheral edge of the grinding wheel 2 will, when reaching its limit of movement against the pin 22, indicate at said peripheral edge the point or height of the plane of the cutting edge of the bit to be ground. If the plane of the cutting edge of the bit as at 25 is brought to such point, indicated at 26, and forced, against the grinding wheel, subsequent of course to the return of the pointer to inactive position as illustrated in Figure 2, the grinding operation of the wheel will be conducted as indicated by the line 21, the same being at an angle of 45 to the axis of the bit, and 90 to the axis of the pointer arm which had established such point, so that the holes within the gauge plate I 5 are numbered in respect to the angle of the grinding operation to the axis of the pointer arm. It will be noted that the guard housing 3 on the grinding unit is rotatably adjustable as by the clamping bolt 29 and suitable nuts therefor, so that it is immaterial at just what angle an operator cares to accomplish the desired functioning of the device, as the setting mechanism will function equally as well.

Furthermore, it will be noted that, if preferred, the plate l5 may be initially set for the proper functioning of the gauge instead of the arm l8 itself, and the arrangement of holes 2| in said plate may be positioned as desired for the work intended.

By this most convenient and simple attachment, an operator may grind a bit having a cutting face of almost any form, the accuracy of same apart from the positive setting of the angle of the grinding depending wholly upon the skill of the operator.

Having thus described my invention, what I claim and desire to secure by Letters Patent, is:

l. The combination with a grinding wheel having a guard housing partially surrounding the same,. of a vertically adjustable work supporting table adjustably mounted upon said housing, and a gauge for predetermining the angle at which work supported upon said table and moved horizontally thereupon toward said wheel will be ground.

2. The combination with a grinding wheel having a guard housing partially surrounding the same, of a vertically adjustable Work supporting table mounted upon said housing, and a gauge for predetermining the angle at which work supported upon said table and moved horizontally thereupon toward said wheel will be ground, said gauge comprising a plate having a plurality of openings therein, a pin engageable within any of said openings, and a pointer swingably mounted and coincident with the periphery of said wheel and limited in its movement in one direction by said pin.

3. The combination with a grinding wheel havingv a guard housing partially surrounding the same, of a vertically adjustable work supporting table mounted upon said housing, and a gauge for predetermining the angle at which work supported upon said table and moved horizontally thereupon toward said wheel after removal of the gauge will be ground, said gauge being pivotally mounted upon said housing coincident with the axis of said wheel and the free end of said gauge being swingable in a path coincident with the periphery of said wheel.

MARTIN HOKANSON. 

